International Workshop on Extremely High Energy Cosmic Rays

International Workshop on Extremely High Energy Cosmic Rays, March 22 -23, 2001, Kashiwa Ge. V-Te. V Gamma-ray Astronomy Masaki Mori ICRR, Univ. Tokyo http: //icrhp 9. icrr. u-tokyo. ac. jp

Gamma-ray astronomy: short history Prediction of nuclear gamma-rays Hayakawa 1952; Morrison 1958 Ground-based Cherenkov: Jelly (1953), Chudakov (1960 -) Prediction of emission from the Crab nebula Cocconi 1959 [nuclear]; Gould 1965 [inverse Compton] Satellites: OSO-3 (1967 -68), SAS-2 (1972 -73), COSB (1975 -82) Compton Gamma Ray Observatory EGRET/COMPTEL/OSSE/BATSE (1991 -2000) Imaging Cherenkov: Whipple, CANGAROO, HEGRA (1980’s-1990’s)

Gamma-ray emission mechanisms ² Gamma-rays are produced in inherently non-thermal processes! +B p+ matter e + h e

CGRO/EGRET Apr 1991 – Jun 2000 30 Me. V – 30 Ge. V 67%=5. 85 (100 Me. V/E)0. 534

EGRET Allsky Map

EGRET: observed intensity Ga lac tic lat itu e de tud i g n o l c Galacti

EGRET: diffuse emission model

EGRET: sources = observed - model

Diffuse gamma-ray spectrum Flatter than expected (E -2. 75): ⇒ Flatter proton/electron spectrum? ? why? Nishimura et al. EGRET JACEE 0 uniform Brems Whipple IC ——————— ——— S. Hunter, Heidelberg WS, 2000

Third EGRET catalog R. C. Hartman et al. , Ap. JS, 1999

EGRET point source summary Pulsars 5 AGN (mostly blazars) Radio galaxy (Cen A) 66 27 (marginal) 1 (marginal) Unidentified 170 Large Magellanic Cloud 1 Solar flare 1 Total 271 (Some may be SNRs) R. C. Hartman et al. , Ap. JS, 1999

Pulsars Radio Princeton catalog (706 pulsars), 1995 Me. V only (Ge. V candidates: 1046 -58, 0656+14, J 0218+4232) Ge. V Thompson, Heidelberg WS, 2000

Pulsars : radio vs gamma-ray Thompson, Heidelberg WS, 2000

Gamma-ray pulsar light curves GLAST proposal

BL Lac’s and EGRET AGNs RED EGRET 3 rd catalog AGNs Green Padovani & Giommi MN 1995 Te. V Whipple, HEGRA, CAT, 7 TA, Durham

Gamma-ray blazars H(igh freq. peaked) BL X(-ray selected) BL L(ow-freq. peaked) BL R(adio-selected) BL Mostly FSRQ and BL Lac’s Mukherjee et al. Ap. J 1997 Lin et al. Ap. J 1999

Multiwavelength spectrum of AGNs Double-peaked structure = synchrotron + inverse Compton Kataoka, Ph. D 2000 PKS 0528+134 (z=2. 1, FSRQ) ↑ ↑ νsync νIC Mrk 421 (z=0. 03, XBL) =γ 2νsync Kubo et al. Ap. J 1998

EGRET unidentified sources Low vs High latitude Persistent vs Variable Geminga-like pulsars? SNRs? OB associations? Gould belt? I. Grenier, Ge. V-Te. V WS, 1999

EGRET un. IDs and SNRs RED EGRET 3 rd catalog un. ID Green D. A. Green’s catalog Te. V HEGRA Ge. V Esposito et al. Ap. J 461, 1996 Te. V CANGAROO

Extragalactic diffuse gamma-rays Single power-law E – 2. 10 0. 03 (30 Me. V-100 Ge. V) Unresolved point sources (ex. Blazars etc. )? Upscattered CMB? E – 2. 10 0. 03 P. Sreekumnar et al. , Ap. J 1998

Imaging Cherenkov technique

Image parameters ● D. J. Fegan, J. Phys. G, 1997 (Simulation)

Example of image cut analysis Hadron rejection power ～ 100 Whipple M. Punch et al. , Nature, 1992 CANGAROO (Vela) T. Yoshikoshi et al. , Ap. J, 1997

Te. V catalog 2000 Classification Object Group Remark Grade A (>5σ, multiple) Crab PSR 1706 -44 Mrk 421 Mrk 501 Many CANGAROO, Durham Many Plerion AGN (BL Lac) Grade B (>5σ) SN 1006 Vela RXJ 1713. 7 -3946 PKS 2155 -304 1 ES 1959+650 BL Lac CANGAROO Durham Utah 7 TA Crimea SNR Plerion SNR AGN (BL Lac) Grade C (strong but with some qualifications) Cas A Cen X-3 1 ES 2344+514 3 C 66 A Geminga B 1509 -58 HEGRA CT Durham Whipple Crimea CANGAROO SNR X-ray binary AGN (BL Lac) AGN (z=0. 44) Pulsar Plerion T. C. Weekes, Heidelberg WS, 2000

Te. V sky 2000

Te. V observations of Plerions S. Fegan, astro-ph/0102324

Crab nebula Unpulsed spectrum Aharonian & Atoyan, astro-ph/9803091 / Heidelberg WS, 2000 synchrotron IC

Crab pulsar spectrum: where is the cutoff? Musquere, 26 th ICRC, 1999

Te. V observations of shell-type SNRs S. Fegan, astro-ph/0102324

Supernova remnant: SN 1006 T. Naito

SNR: SN 1006 - interpretation Synch+IC Only IC? No protons? Naito et al. Astron. Nach. 320, 1999

Te. V observations of AGNs (Detection of 1 ES 1426+428 (z=0. 13) is claimed by Whipple but not published) Krennrich, astro-ph/0101120

AGN: Mrk 421 variability Time scale < a few hours Correlation with X-ray flux Gaidos et al. , Nature, 383, 1996 Takahashi et al. Ap. J 542, 2000

AGN: Mrk 421 spectrum z=0. 031 Synchrotron + inverse Compton model works well ⇒ e origin Proton model still possible One-zone SSC model δ=14, B=0. 14 G Takahashi et al. Ap. J 542, 2000 synchrotron inverse Compton

AGN: Te. V gamma-ray absorption by IR background IR Background Mean free path for e+epair production Protheroe et al. astro-ph/0005349

AGN: Mrk 501 spectrum z=0. 033 Crisis? ↓ Protheroe et al. astro-ph/0005349 Aharonian et al. A&Ap 349, 1999

Next generation projects Satellites Me. V: INTEGRAL 15 ke. V-10 Me. V, 2002 ACT (Advanced Compton Telescope) 300 ke. V-20 Me. V, 2008? Ge. V: AGILE 30 Me. V-50 Ge. V, 2003 GLAST 20 Me. V-300 Ge. V, 2005? Ground-based CANGAROO-III 4 10 m, Australia, 2000 -2004 MAGIC 1 17 m, Canary Island, 2001 HESS 4 12 m, Namibia, 2002 VERITAS 7 10 m, Arizona, 2004 -

Sensitivity of future detectors

Summary Gamma-ray observation maps the non-thermal Universe! Plerions (pulsar nebula) Inverse Compton? ⇔ synchrotron origin? Pulsars Cutoff in pulse component? ⇔ polar cap/outer gap SNRs π0 contribution? ⇔ cosmic ray origin AGNs Gamma-ray source: e± or p? Intergalactic IR ⇔ cosmology EGRET un. IDs, Neutralinos, GRBs, QG, Galactic/extragalactic diffuse, …, and more?